Synchronous-type fluid-blast circuit interrupters having spaced nozzleshaped contacts



Dec. 13, 1966 F. KESSELRING "TYPE FLUID-BLAST CIRCUIT INTERRUPT NGSPACED NOZZLE 3,291,950 ERS -SHAPED CONTACTS SYN CHRON OUS HAVI 5Sheets-Sheet 1 Original Filed March 27, 1961 INVENTOR Frirz Kesselring.

BY W4.

ATTORNEY Dec. 13, 1966 F. KESSELRING 3,291,950

SYNCHRONOUS-TYPE FLUID-BLAST CIRCUIT INTERRUPTERS HAVING SPACEDNOZZLE-SHAPED CONTACTS Original Filed March 27, 1961 5 Sheets-Sheet 2United States Patent 3,291,950 SYN CHRONOUS-TYPE FLUID-BLAST CIRCUITINTERRUPTERS HAVING SPACED NOZZLE- SHAPED CONTACTS Fritz Kesselring,Zurich, Switzerland, assignor to Siemens- SchuckertwerkeAlrtiengesellschaft, Erlangen, Germany, a corporation of GermanyOriginal application Mar. 27, 1961, Ser. No. 98,522, now Patent No.3,215,804, dated Nov. 2, 1965. Divided and this application June 10,1965, Ser. No. 462,936 11 Claims. (Cl. 200-148) This application is adivisional application of patent application filed March 27, 1961,Serial No. 98,522, now US. Patent 3,215,804, issued November 2, 1965, toFritz Kesselring.

This invention relates to synchronous-type fluid-b1ast circuitinterrupters in general and, more particularly, to improved interruptingstructures therefor.

A general object of the present invention is to provide an improvedsynchronous-type fluid-blast circuit interrupter which will be highlyefficient and which will utilize a minimum quantity of arc-extinguishingfluid.

Another object of the present invention is to provide an improvedcompressed-gas circuit interrupter in which the application of thearc-extinguishing medium is dependent upon a predetermined reduction inmagnitude of the value of the instantaneous current being interrupted.

Still a further object of the present invention is the provision ofimproved compressed-gas circuit-interrupting structures in which moreeffective use of the gas-blast medium is obtained by the employment ofsynchronouslyoperated valve structures.

In United States patent application filed, March 22, 1961, Serial No.97,656, now US. Patent 3,215,866, issued November 2, 1965 to FritzKesselring and Lutz Seguin and assigned to the assignee of the instantapplication, there are disclosed and claimed novel-type synchronousoperators particularly suitable for synchronously-operatedcircuit-interrupting devices. It is a further object of the presentinvention to utilize the principles set forth in the aforesaid patentapplication rendering them highly efiicient as applied tocircuit-interrupting devices.

Additional objects and advantages will readily become apparent uponreading the following specification, taken in conjunction With thedrawings, in which:

FIGS. 1 and 2 illustrate time graphs of energy input into circuitinterrupters of conventional type and those embodying features of thepresent invention during the circuit-interrupting operation;

FIG. 3 is a somewhat diagrammatic view taken in vertical cross-sectionthrough a compressed-gas-type of circuit interrupter embodying featuresof the present invention, the contact structure being illustrated in thepartially open-circuit position;

FIGS. 4-7 illustrate novel types of blast-valve arrangements embodyingfeatures of the present invention:

FIG. 8 illustrates a perspective view of a double-valve arrangementembodying features of the present invention;

FIG. 9 is a composite vertical sectional view taken through acompressed-gas circuit interrupter embodying features of the presentinvention, the left-hand portion, designated FIG. 9A, showing theclosed-circuit position, and the right-hand portion, designated FIG. 9B,showing the open-circuit position;

FIG. 10 is a vertical sectional view taken through a modified type ofcompressed-gas circuit interrupter, the contact structure beingillustrated in the closed-circuit position; and,

FIGS. 11 and 12 illustrate in vertical section and plan views,respectively, a modified type of orifice construction for the circuitinterrupter of FIG. 10.

Referring to the drawings, and more particularly to FIGS. 1 and 2thereof, it will be noted that the stresses exerted upon theinterrupting chambers of electrical circuit interrupters are determinedin accordance with their design by the maximum interrupting are power orthe maximum are work dissipated. The latter case occurs When thepressure produced by the arc cannot be continuously equalized throughoutthe breaker, as it happens to be, for example, in oil circuit breakers.As it is known, the interrupting work A is given by the equation:

Where:

b=instantaneous value of the arcing voltage, i=instantaneous value ofthe current, and t =arcing time.

It has been found that the mean value of the current i and, mostimportantly, the arcing time t can be reduced by control ofsynchronization. In single-phase circuit breakers the control ofsynchronization is applied in a relatively easy manner. On the otherhand, in the case of polyphase circuit breakers, for frequencies of 50or 60 cycles, considerable difiiculties are often encountered. This factcan be seen at once in that the mass of the moving system necessary forlarge rated currents cannot be brought satisfactorily to the separateddistance necessary for arc-extinguishing action in a sufficiently shorttime, for example, in .1 millisecond. Also, the current wave is not assingularly defined as in the case of singlephase circuit breakers. When,for example, a two-phase arcing short circuit changes shortly, beforepassage through current zero, into a three-phase short circuit, thecurrent wave changes considerably, which may lead to faulty switching.Furthermore, the maintenance of so-called flashover interruptions undercontrol presents considerable difficulties because of the then resultingextraordinary high are power.

It is known that the value of the arc voltage depends very much on whatkind of effect the quenching medium has upon the arc. If the arc isdrawn in a still atmosphere, then the arc-voltage gradient isapproximately 20 to 30 volts/centimeter. On the other hand, if the arcis subjected to, for example, intensive axial blasting, or, if in thegas-vapor atmosphere surrounding the are under high pressure, thereoccurs a sudden expansion, then the arc-voltage gradient reaches 200volts/centimeter, and more. In the case of the transition from little,or only slightly affected arcs, to strongly affected arcs, thearc-voltage gradient and the corresponding arc voltage changes by afactor of approximately 10.

The present invention, in part is concerned With a fluid-blast circuitbreaker, especially suitable for altermating-current interruptions, inwhich, as contrasted with known breakers, the interrupting work to bedissipated is considerably reduced. The present invention is, in part,distinguished by the fact that there is provided a control, which makesthe quenching medium, serving for arc-extinguishing action in the caseof arbitrary interruption times, effective only when the current isdecreasing, specifically 0.5 to 2.0 milliseconds before the currentpasses through current zero.

The advantages of fluid-blast circuit breakers constructed in accordancewith the present invention can be seen clearly from a comparison ofFIGS. 1 and 2 of the drawings. In both figures i is the interruptedcurrent, [L is the arc voltage, and t is the arcing time. The contactseparation follows arbitrarily at instant t At instant t there occursthe first passage of the current through current zero. However, thecontact separation is still so small that the interruption of the arcdoes not take place. At the instant t the necessary separation distanceis assumed to be reached and, therefore, the arc-quenching action shouldfollow, whereby it is assumed that in both cases the maximum arc voltagett occurs. Breakers of known design provide, shortly after the contactseparation, immediately intensive arc-extinguishing action, which leadsto increased arc voltage ,u On the contrary, in the case of circuitbreakers constructed according to the present invention, intensiveeffect upon the arc can be found only in intervals t -t and t -t The arcvoltage will, therefore, remain very small in magnitude up to theinstant t and increase correspondingly only toward the passage throughcurrent zero i This results in that the interrupting work, representedby the shaded area A as illustrated in FIG. 2, is only a fraction of theinterrupting work A as shown in FIG. 1, being approximately in theillustrated example taken from an actual case. In addition, there existsalso a considerably lower maximum are power N which amounts toapproximately one-half of N correspondingly, the stresses from pressurein the case of circuit breakers, constructed in accordance with thepresent invention, are considerably lower, which makes possible alighter design of the interrupting chamber and leads consequently tolower production costs.

Still a further improvement can be obtained by constructing circuitbreakers in accordance with the present invention in that the intensityof quenching can be made dependent upon the magnitude of rate ofdecrease of the interrupted current, that is (-di/dt/). As well known,the quenching intensity must be the greater the greater is theinstantaneous rate of change of the interrupted current immediatelybefore the passage through current zero, and the greater is the slope ofthe recovery voltage. The latter is generally given by the networkconditions and the magnitude of the interrupted shortcircuit current.For a higher short-circuit current and thereby for a higher rate ofchange of the short-circuit current, there corresponds most of the timealso a higher slope of the recovery voltage, because the inductance ofthe oscillating circuit at higher short-circuit intensitiesiscorrespondingly lower. If also the intensity of arc quenching is madegreater, the greater is the rate of decrease of the interrupted current,then it can be expected that the arc quenching takes place with lesspossibleeffort, and also lowest overvoltage over the entire currentrange from very small currents up to full shortcircuit currentintensities. As well known, for example, in disconnecting a transformerrunning at no-load, a very high overvoltage occurs, because thequenching intensity is, very often too high relative to the smallno-load current, for example, only amperes. The arc then interrupts toosoon, which results in an instantaneous release of the large amount ofmagnetic energy stored in the transformer under a stronger build-up ofthe over- .voltage. In case of compressed-gas circuit breakers, amatching of the intensity of interrupting conditions to the slope ofcurrent shortly before passage through current zero has an additionaladvantage in that the consumption of compressed air at normal switchingoperations is considerably reduced.

FIG. 3 shows by way of example a form of construction of compressed-gascircuit interrupter constructed in accordance with the presentinvention. With reference to FIG. 3, the reference numeral 1 indicatesan interrupting chamber in the form of an insulating cylinder. Atthetop, the interrupting chamber 1 supports the interrupting nozzle contact2 having a terminal lead 3. The bottom of the insulating cylinder 1 isclosed by a closure cap 4 having a second terminal lead 5. The referencenumeral 6 indicates cooperable sliding contacts which carry the currentfrom the terminal lead 5 to the movable contact rod 7. The compressedgas is brought into the interrupting chamber 1 through an electricallyactuated valve 8 and an insulating blast tube 9. The reference numeral10 indicates a rotatable valve damper shown in the open position in FIG.3. It is actuated by a moving coil or armature 11, which rotates in thefield of an electromagnetic system 12 excited by the interruptingcurrent, as set forth in the aforesaid United States patent application.

The reference numeral 13 denotes an operating cylinder, which isconnected through a tube 14 with the insulating blast tube 9. A piston15, movable within the operating cylinder 13, is acted upon by acompression spring 16. An insulating operating rod 18 is supported upona pivot 17, and is coupled with the piston 15 through a driving link 19.The rod 18 is also connected with the movable contact rod 7 by means ofa pivot pin 20. In the open-circuit position, shown by the dotted lines7a, the insulating operating rod 18 is held by a rotatable latch 21against the biasing action exerted by the compression spring 16.

The circuit interrupter, generally designated by the reference numeral22 and set forth in FIG. 3, functions in the following manner: At anarbitrary instant t the electromagnetically actuated valve 8 is assumedto be opened. This action results in exposing the piston 15 to theentering blast of compressed gas, which will cause the piston 15 to movedownwardly against the biasing action exerted by the compression spring16 until the movable contact rod 7 reaches the illustrated open position7a of completed interruption. Now, if the current is increasing duringthis process, then an induced current will flow through the moving coilor armature 11, which will, together with the flux in the magneticsystem 12, produce in the air gap a torque, which causes the rotatablevalve damper 10 to turn to a closed position. In this connection, it isto be noted that the magnetic circuit 12 encompasses the main currentpath L L and consequently has flux generated therein corresponding tothe line current. As a result, if at first the compressed air cannotenter the interrupting chamber 1 to blast the arc, the are 23 burns witha much lower arc voltage than would be the case otherwise. Now, if themain current begins to decrease, then the current induced in the movingcoil 11 will change its sign as set forth in the aforesaid United StatesPatent 3,215,866. The torque is then reversed, and the valve damper 10will now assume the illustrated open position. By util ization ofsaturation of the magnetic system 12, it can be obtained that thecurrent induced in the moving coil 11 begins to flow 0.5 to 2milliseconds before the passage of the current through current zero.Now, at this time the compressed air may enter the interrupting chamber1 from the blast tube 9 and act intensively upon the are 2311 drawnwithin the nozzle 2, thereby bringing about interruption of the arc 23aand consequent circuit interruption.

If, on the contrary, a transformer operating at noload should bedisconnected, and if, as a result of buildup of overvoltage causing ashort circuit shortly before the no-load current of the transformerpasses through current zero, then the current immediately sharplyincreases. This results in the situation whereby the valve damper 10will be instantly moved into the closed position by the moving coil 11,by which action the passage of the flowing gas upon the arc 23a isstopped. The are has a high current intensity but a very low arcingvoltage. Later, when the current again begins to de crease, the valvedamper 10 will then open and the arc quenching action will follow.

If the valve damper 10 is supported upon the rotatable shaft 11a of themoving armature 11, then it can be obtained in a relatively simplemanner that the valve damper 10 opens wider the more quickly the linecurrent decreases toward current zero. As a result, it is possible tomatch or correlate the intensity of quenching to the intensity of theinterrupted current, especially to the slope with which it passesthrough current zero. For this purpose, it may be suitable to establishthe normal at rest position of the valve damper in such a position thatthe minimum intensity of quenching, necessary for interruption ofcurrents in the normal operating range, is provided. It now highercurrents are to be interrupted, then automatically a correspondinglylarger movement of the valve damper 10 takes place, so that again theintensity of quenching is adjusted to the prevailing conditions.

If, for example, in the case of interrupters using liquids, an expansionshould be introduced, then blocking of a valve 10 during increasingcurrent can be released when the current begins to decrease towardcurrent zero, in which case it may be suitable to introduce theexpansion shortly before the passage of the current through currentzero.

The advantage of circuit breakers constructed according to the presentinvention consists largely in that the breaker mechanism itself can bebuilt in the generally conventional manner, and does not need to moveespecially fast as is necessary in the case of conventional synchronizedbreakers. The control is limited entirely to the matching or correlatingof the intensity of interrupting action to the prevailing conditions,which can be done at a small cost. The interrupting capacity of breakersof the type built according to the present invention can be, although atapproximately the same production cost as conventional breakers,increased to several times the value so far obtained.

It is known in the valve art to provide arrangements including arotatable wind-type valve adapted to be electrically operated anddisposed within a cylindrical opening. With valves of this type it isdesirable that the valve, when closed, have a very tight fit and, whenopened, permit optimum flow conditions to take place. Opening of suchvalves is usually effected by rotating the valve about 90. Theelectrical drive may comprise either a motor or a magnetic drive. If itis desired to provide valves which have a short operating time fromclosed condition to open condition, or vice versa, of less than of asecond particularly less than one millisecond, certain problems areencountered at once. Such extremely fast-acting valves are needed, forexample, for compressed-fluid electrical switches in which areextinction is effected by a flowing medium. In such switches, or circuitbreakers it is necessary that the valves be operated, for example, at acertain instant, within one current half-cycle. It is not absolutelynecessary in circuit breakers for the valve to establish a perfect sealwhen closed, for a small amount of leakage is not objectionable sincethe quick-acting valve usually has connected in series therewith anothertightly-closed valve, such as indicated by the reference numeral 27 inFIG. 4, which may be of conventional design.

According to one aspect of the present invention as shown in FIGS. 4 and5, the valve arrangement including at least one electrically-operatedrotatable wing valve disposed in a cylindrical opening is characterizedin that the cross-section of the rotary wing, or wings perpendicular tothe axis of rotation is biangular for obtaining opening and closingtimes of less than 10 milliseconds, the width b of the axial sealingsurfaces of the rotatable wing amounting to only a fraction of themaximum wing thickness d, and the width of the rectangular valve openingB being no more than equal to the radius r of the rotatable wing.

In FIGS. 4 and 5 of the drawings, a valve arrangement, according to theinvention, is shown schematically in the closed and open positions,respectively. FIGS. 6 and 7 illustrate a similar valve arrangement whichoifers particularly little resistance to flow, and FIG. 8 showsa doublevalve arrangement including two rotatable wing valves actuated by asingle moving-coil system.

In FIGS. 4 and 5, the reference numeral 31 designates a cylindricalvalve casing and the reference numeral 32 indicates the wing-valvecomprising two plates 33 and 34 rigidly connected to the shaft 35. Theaxial sealing surfaces are indicated at 36. The reference numeral 37designates rectangular inlet, and the reference numeral 38 designatesthe rectangular outlet. In FIG. 4 of the drawings, the pressure P actsupon the upper surface 33 of the rotatable wing valve 32. Since thepressure distribution relative to the axis of rotation 35 issymmetrical, substantially no resultant torque is applied to thewingvalve 32.

FIG. .5 shows the valve in its fully opened position, and this figurealso illustrates the fact that the torsional moment, or torque actingupon the wing valve 32 is zero. Contrary to the positioning of the valve32 shown in FIG. 4 in which there exists a stable equilibrium, theequilibrium in the open position, as shown in FIG. 5 is unstable. Assoon as the wing valve is moved somewhat from its symmetrical position,it tends to move to its closed position, and the maximum closing forceis effective approximately in the position indicated by broken lines 32ain FIG. 5. Accurate measurements taken with the valve arrangementaccording to FIG. 4 and involving the values 1:6 millimeters, B=5millimeters, d:3 millimeters, and a wing height of 30 millimetersindicated at l to 6 atmospheres over-pressure on the inlet side, resultin a maximum torque in the closing direction of about pond (gram weight)centimeters, that is, an extraordinarily small value which, however, isobtainable only when ball bearings are being used.

The width of the axial sealing surface of the rotatable wing valve was19:12 millimeters, and the sealing gap amounted to about millimeter. Theresultant leakage loss at 6 atmospheres was 2 cm. ms. relative to normalpressure and normal temperature. With a gap thickness of millimeter, itwas possible to reduce the leakage loss to 0.9 cmP/ms. Sealing canfurther be improved by providing at least along the axial sealingsurfaces of the rotatable wing sealing strips, which are biasedoutwardly, such as used, for example in rotary-piston type motors.

The embodiment illustrated in FIGS. 4 and 5 of thedrawings has thefollowing advantages: The moment of inertia of the rotatable wing valve32 is very small. Despite this, however, the stability is high due tothe boxtype construction. In order to fully open the valve, an angularmovement of the wing only of 04/2 is required. The torque necessary tomove the rotatable wing is very small. The resistance to flow of theopened valve is negligible. The use of wings having a height which issubstantially larger than their diameter makes it possible to obtainlarge cross-sectional flow areas with valves of minimum dimensions.

FIGS. 6 and 7 illustrate an embodiment of the invention providing avalve arrangement for still better flow conditions. The rotatable wing42, which is movable within the casing 41 has an airfoil or streamlinedprofile. It may be formed, together with the shaft 43, by die-casting,for example, from an aluminum or magnesium alloy, the moment of inertiabeing further reduced by the axial openings 44. Furthermore, the casing41 may have disposed therein liners 45 and 46, as shown in FIG. 7, whichare favorable to the streamline flow of the medium.

FIG. 8 shows an embodiment valves 51 and 52 of the type illustrated inFIGS. 4 and 5. Yalve 51 is shown in its open position, whereas valve 5215 shown in its closed position. Indicated generally at 53 is amoving-coil system, the moving coil 54 of which is secured to the commonshaft 55. The coil ends of coil 54 extend to the slip rings 56 and 57and are connected through brushes 58 and 59 and a switch 60 to a battery61. The pole pieces of the moving-coil system are indicated at 62 and63.

As the double throw switch 60 is moved from the of the inventionutilizing center position, indicated by broken lines, to the upperposition, current will flow through coil 54 in the direction indicatedby the arrow, said current, together with the air-gap inductionproducing a torque which causes the valve 51 to be moved to its closedposition and valve 52 to be moved to its open position.

Referring to FIG. 8, the rotary wing of valve 51 tends to move clockwiseto its closed position, whereas the rotary wing of valve 52 tends tomove counter-clockwise also to its closed position, as shown. It is,therefore, apparent that the two torques of the rotary wings 51, 52substantially cancel each other. Movement of switch 60 to its lowerposition effects a reversal of the current flowing through coil 54,which, in turn, also reverses the torque. Thus, the two rotary wings ofvalves 51 and 52 return to the position shown.

Tests have proven that with an arrangement such as shown in FIG. 8, itis readily possible to effect movement through the angle a/Z (FIG. 4) inless than 1 millisecond. The moment of inertia of one rotary wingincluding the shaft amounts to only about 10% of the moment of inertiaof the moving coil 54.

In one practical example, the main driving torque of the moving-coilsystem amounted to approximately 12 kpcm., whereas the resultant maximumcounter-torque acting upon the rotary wings amounted to only about 0.03kpcm., that is, to only 2.5% of the driving torque, at 6 atmospheres ofover-pressure.

The battery 61 may be replaced by a charged condenser, which, whendischarged, causes a very high impulse-like current to flow through themoving coil 54. Furthermore, the permanent magnet system 62 and 63 maybe replaced by an unsaturated, or saturated alterhating-current magnet.If this is the case, and if coil 54 is supplied from a source of directcurrent, the rotary wings will oscillate at the frequency of thealternating current.

If it is desired to use the valve arrangement according to the inventionfor the control of fluid-blast circuit breakers, it is desirable toenergize the magnetic system 62 and 63 in dependency upon the current tobe interrupted, whereas the moving coil 54 should be supplied with acurrent which may be proportional, for example, to the changing rate ofthe current to be interrupted. In this manner, it is possible to causevalve 51 to open only when the current decreases, particularly shortlybefore the zero passage of the current, and to be closed during theincrease of the current, during which period the circuit breaker isvented by the valve 52, as illustrated in FIG. 10, hereinafterdescribed. In view of the extraordinarily short response time of thesevalves 51 and 52, the valve arrangement embodying the invention may beused advantageously in connection with control and regulating systems.

In circuit-breaker techniques there exists a common tendency toemphasize the time characteristic of the switching device. This isespecially of importance when the switching operation should take placeat a definite instant within a half-cycle of the alternating current, ornear the passing through current zero in the case of a DC. reversingcurrent, as it may be required for synchronized breakers, high-speedbreakers, regulating equipment, and rectifiers. Up to now, thehigh-voltage breaker devices were generally built with tulip-shaped, ornozzle-like stationary contacts and movable contact pins. However, thereare also known designs in which a nozzle is moved axially to obtain theinterruption. All of these designs involve a large mass of movableparts, especially for current ratings over 400 amperes.

An aspect of the present invention covers an electrical switching deviceoperated by compressed medium, with one stationary and one movablecontact system, which is subjected to opposing forces. Theabove-mentioned disadvantages are avoided in that the stationary contactsystem has at least two electrodes, and at least one of these has .anozzle-like shape. Preferably the stationary contact system issurrounded by an electrically insulating shell, inside of which isarranged the movable contact system, whereby for intreruption there isprovided inside of the shell a pressure by which the movable contactsystem is brought into the open position, and that the stationarycontact system is arranged so that the interrupting arc, which is drawnwhen he contacts are separated, is driven into the nozzle opening andextinguished.

FIGS. 9 and 10 generally describe examples of two forms of compressedgas circuit-breaker arrangements constructed in accordance with thepresent invention. FIG. 9 is a composite view with FIG. 9A illustratingthe breaker in the closed-circuit position, whereas FIG. 9B illustratesthe breaker during the opening operation with arcing being established.FIG. 11 shows a special form of design of the stationary contact system.

In FIG. 9, the reference numeral 81 indicates a conducting nozzle havingan orifice opening 82, opposite to which is arranged another conductingnozzle 83 having a smaller orifice opening 84. The conducting nozzle 81is connected with a spider piece 85 which supports the upper terminallead 86 and the arcing electrode 87 of the interrupter. The nozzle 83 isconnected with a spider member 88, which supports the lower terminallead 89 and the arcing electrode 90. The reference numeral 91 indicatesmovable contact segments arranged peripherally along the outercircumference of the conducting nozzles. They are connected to pistons92 and are pressed against the conducting nozzles 81 and 83 bycompression springs 93. The operating cylinders 94 in the insulatingchamber 95, in which the pistons 92 are moving, are closed by a threadedcover 96. The contacts 91 and the pistons 92 are interconnected byoperating rods 97 having hookshaped portions 98, which, in the openposition, engage under angular latches 99, whereby the segmental movablecontacts 91 are held in the open-circuit position.

At the outer side of the nozzle 81 there is arranged an insulatingexhaust casing 100 which is widened toward its upper end, and which isclosed by a perforated cover 101. An inlet 102 is provided for themedium being held under pressure. For cooling and noise suppressionpurposes the space 103 may be filled with various cooling devices, suchas screening, concentric metallic tubes, or the like (not shown).

The opening operation of the compressed-gas circuit interrupter 80 ofFIG. 9 is as follows: When the valve 104 is opened, the medium, such asgas held under pressure, flows through the opening 102 into theinterrupting chamber 95. As a result, the movable pistons 92 and withthem the movable segmental contacts 91 are forced radially outwardlytoward the outside of the interrupting chamber 95 against the actionexerted by the compression springs 93. This action happens very quicklydue to the small moving masses. The short arcs 105 and 106 (FIG. 9B)terminate on the contacts 91 as they are being opened, and areimmediately driven inwardly along the nozzle surfaces 107, 108 by theinwardly directed flow of the quenching medium. This action is augmentedby the electrodynamic forces present. The merged arc 109, terminatingbetween the arcing electrodes 87 and 90, is extinguished by theaxially-flowing gas blast. The hook portions 98 secured to the guiderods 97 of the contacts 91 are held in the open-circuit position by thelatches 99, as illustrated in FIG. 9B of the dnawings. This concludesthe opening operation of the interrupter 80.

For initiating the closing operation, the latches 99 are withdrawn by acontrol device, not shown in the figure. The result of this is that thecontact pieces 91 move back into the closed position, as shown in FIG.9A, under the biasing force of the compression springs 93. The valve 104is purposely controlled by a synchronous operator in accordance with theteaching of the aforesaid patent application Serial No. 97,656 so thattheflow of the cornpnessed medium starts only when the current isdecreasing, specifically shortly before the passage of the currentthrough the zero value.

The control valve 104 is opened during descending values of theinstantaneous current i being interrupted in accordance with theteaching of the aforesaid patent application Serial No. 97.656. Thesynchronous operator 110 includes a magnetic circuit 111 and a movingcoil system, or armature 112. The moving coil system 112 includes amoving coil 113 comprising a Winding closed upon itself and may consistof a rectangular copper or aluminum frame. The magnetic circuit 111 isenergized by the current i to be interrupted. The current i sets up amagnetic field in the magnetic circuit 111, which induces a current i inthe closed frame 113. The flux I causes an induction B in the air gap114. The magnetic circuit 111 becomes saturated during peakinstantaneous values of the short-circuit current i Near a current zeroon the descending part of the current wave the core 111 unsaturates, rdecreases rapidly in value inducing i and a torque is created at thistime in the control shaft 115 opening the valve 104. Reference may behad to FIG. 3 of the aforesaid application for a detailed discussion ofthe theory of operation. The small opening 84 in the nozzle 83 hasparticularly the function to remove the for-med metallic vapors to thelower part of the interrupting chamber whereby a subsequent openingoperation is substantially improved without the air consumption beingnoticeably increased.

FIG. shows another form of compressed-gas breaker design according tothe present invention including the circulation of the compressed mediumand an additional interrupting gap. The nozzle-like stationary contacts119, 120 are connected to spider members 121 and 122. The upper terminallead is designated by the reference numeral 123. A contact extension 124is slidably connected with a movable contact cluster 125, which in theclosed \position, provides a contact with a lower terminal lead 126. Themovable contact finger assembly 125 is moved up or down by means of apivotally mounted insulating lever 127 which is held in an elastome-ricsleeve 128, such as synthetic rubber.

The movable segmental contacts 129 are mounted on the inner surface ofan elastomeric, or rubber-like sleeve member 130, which provides thedesired contact pressure between the movable contacts 129 and therelatively stationary contacts 119, 120. The reference numeral 131designates a rotary double-damper valve operating according to thedescription of the invention pertaining to FIG. 8 of the drawingsthrough which the quenching medium flows from a high-pressure tank 132through the Valve 51 and enters into the space formed by the rubbersleeve 130, while the reference numeral 52 indicating a correspondingcompanion rotary damper valve, which is connected to the low-pressuretank 133 and which, when opened, provides the discharge from the arcingchamber 1354.

The interrupting gases are exhausted from the nozzle openings 135, 136and can escape through the openings into the low-pressure space. Theentire interrupting space is enclosed by an insulating container 138with end closer caps 139 and 140. In the case of compressed-gasbreakers, a low pressure of say 2.5 to 7.5 atmospheres, [for exampledepending upon the operating voltage, can be used, While the highpressure can be set suitably to approximately 6 to 12 atmospheres, forexample. A compressor, not shown, can be provided between thelowpressure tank 133 and the concentric high-pressure tank 132. The highpressure tank 132 is tightly sealed off from the rotary damper valve131, and thus from the inside of the insulating cylinder 138 by aconventional series blast valve 27. By means of a magnet system 141,shown by the dotted lines, which acts upon a moving coil 53 it can bearranged that the damper valve 51 opens only when the current isdecreasing, especially shortly before the current passes through itscurrent-zero value.

FIG. 11 shows in vertical section and HQ. 12 in a horizontal view of amodified form of the lower nozzle-like electrode a with especiallystrong electrodynamic effect upon the arc. The stationary contact 120ais provided with radial slits 142. For improvement of flow distribution,inside of the contact there is arranged an insulating flow piece 143,which opens downwardly and which lf'O'I the purpose of guiding the arc,extends somewhat beyond the slits 14 2. Should an arc start, for exampleat point 144, then due to the dynamic force affecting the current loop,this are will be moved along the dotted line toward the nozzle opening145 and extinguished with a greater speed.

The breaker arrangement illustrated in FIGS. 10-12 operates in thefollowing manner: The interruption of the current is started by openingthe valve 27 at any assumed time. Up to heavy overcurrents the dampervalve 51 maintains the illustrated open position. The compressed gasenters the inside of the rubber sleeve 130, and infiates it, whereby themovable contacts 129 are moved away from the nozzles 119 and 120. Thearcs, appearing at the opening of the contacts 129, are driven insideand are quenched in the nozzle system. At higher overcurrents, andespecially at short-circuit currents, valve 27 will be opened, forexample, by the respective overcurrent or protective relay or byselective operation in which case it is of advantage to take suchmeasures, that the opening of valve 27 is possible only when the currentis increasing. The damper valve 51 is then at first in the closedposition and is opened by the action of the magnetic system 141 and themoving coil 53 only when the current is decreasing, whereby the dampervalve 52 is immediately closed. The interruption of the current thenfollows in the described manner. With a certain amount of time lag,although before closing of the valve 27, the movable contact fingerassembly is moved upwards by the rod 127 so that an open isolating gapappears between the contact cluster 125 and the upper end of the lead126. After the valve 27 has been closed, the inside space of the rubbersleeve 130 is exhausted. This results in that the movable contacts 129may move back into the illustrated closed position. The closing of thecircuit is subsequently achieved by moving the contact cluster 125downwards into the position as shown in FIG. 10.

Should it happen, that the arc does not go out, then the moving coil 53,immediately after the current passes through current zero, turns in theopposite direction, causing thereby the damper valve 51 to close and thedamper valve 52 to open. This results in immediate release of pressureinside of the rubber sleeve 130. The movable contacts 129 move into theclosed position, the arc is short-circuited and is extinguished. As soonas the current again begins to decrease, the above-describedinterrupting process is repeated.

In order to increase the speed of interruption it can be of advantage toprovide reinforcing segments 146 on the rubber sleeve 130. If thesesegments are solidly connected with the rubber hose, for example, byvulcanizing, then the elastic constant and consequently, also thecon-tact pressure in the closed position are increased.

Switching arrangements according to this invention have significantadvantages. The quenching system proper, consisting of a simple,asymmetrical or symmetrical double nozzle, due to favorable distributionof the electric field and optimum fiow distribution, results inexcellent quenching effectiveness. Through application of constantstatic relatively low pressure inside of the system, a higher dielectricstrength in the open position can be obtained despite a smaller opengap. The adaptation to higher voltages can be obtained in a simplemanner by increasing the static pressure inside of the chamber 134 sothat it is possible, for example, with the very same chamber, to buildbreakers from 6 to 30 kv., which has considerable advantages withrespect to manufacturing cost and stock maintenance.

The dimensions of the chamber 134 itself can be held small, especiallywhen a synchronized control is provided. In case of designs with gascirculation the usual annoying, explosion-like noise of compresesd-gasbreakers is completely suppressed. With respect to their quenchingeffectiveness and higher dielectric strength, also some especiallysuitable gases can be used, such as carbon dioxide CO electro-negativegases, for example sulfurhexafluoride gas SP But it is also possible tooperate the breakers according to this invention with insulatingliquids, which are forced in a suitable manner through the nozzleopenings. Also in this case it is possible and recommended to usesynchronized control in which the flow of quenching medium is startedonly when the current is decreasing, especially shortly before it ispassing through zero, which is of special advantage because ofconsequent small interrupting work and, therefore, practicallyeliminated back-pressure.

The total mass of the movable contacts 129 can be held very low also athigh-rated currents (1000 amps. and more). For example, the weight ofone of the eight movable contact pieces of a 1250 amp. breaker amountsto only 1.5 pond (gram weight) while the breaker can interrupt asymmetrical short circuit current of 30 kiloamperes and a momentaryshort circuit current of 70 kiloamperes which corresponds tointerrupting capacity of 500 mva. at 10 kv., or 1500 mva. at 30 kv. Dueto these extremely small masses, the acceleration of the movablecontacts can reach 5000 g. and more. Because, due to the static gaspressure or to the insulating liquid utilized, and the application ofdouble interrupting gaps, only small gaps of a few millimeters arenecessary, the interrupting time of a fraction of one millisecond isobtainable. If there is arranged an additional interrupting gap, inseries with the main interrupting system, then in the open position thevoltage stress falls essentially on this second interrupting gap. Thismakes is possible to reduce some more the striking distance of the maininterrupting gap and, therefore, the interrupting time. If theadditional interrupting gap is built at the same time also forinterrupting of smaller switching loads, then a resistance 148 (See FIG.10) can be connected in parallel to the main interrupting gap, wherebythe rise of recovery voltage is reduced, and the interrupting capacityis correspondingly increased.

Although there have been illustrated and described specific structures,it is to be clearly understood that the same were merely for the purposeof illustration, and that changes and modifications may readily be madetherein by those skilled in the art, without departing from the spiritand scope of the invention.

I claim as my invention:

1. The combination in a fluid blast circuit interrupter of a pair ofspaced relatively fixed nozzle-shaped contacts, a plurality of movablebridging segmental contacts for bridging said pair of spaced relativelyfixed nozzle-shaped contacts in the closed circuit position of theinterrupter, each of said segmental bridging contacts having a pistonmember secured thereto, blast valve means including a synchronousoperator for releasing a blast of compressed fluid into the circuitinterrupter for acting upon the several piston members for effecting arcestablishment, means for directing the fluid blast radially inwardlytoward the nozzle openings of said pair of relatively fixed nozzleshapedcontacts, said synchronous operator being effective to cause blast valveopening only near a current zero on the descending part of the currentwave, and a pair of spaced relatively fixed arcing electrodes disposedalong the axis of the nozzle-shaped contacts for positioning the arcaxially along the nozzle-shaped openings of the contacts.

2. The combination in a fluid blast circuit interrupter of a pair ofspaced relatively fixed nozzle-shaped contacts, a plurality of movablebridging segmental contacts for bridging said pair of spaced relativelyfixed nozzle-shaped contacts in the closed circuit position of theinterrupter,

each of said segmental bridging contacts having a piston member securedthereto, blast valve means including a synchronous operator forreleasing a blast of compressed fluid into the circuit interrupter foracting upon the several piston members for effecting arc establishment,means for directing the fluid blast radially inwardly toward the nozzleopenings of said pair of relatively fixed nozzle-shaped contacts, saidsynchronous operator being effective to cause blast valve opening onlynear a current zero on the descending part of the current wave, a pairof spaced relatively fixed arcing electrodes disposed along the axis ofthe nozzle-shaped contacts for positioning the arc axially along thenozzle-shaped openings of the contacts, and latching means for latchingthe piston members in the open circuit position for effecting circuitisolation.

3. A compressed-gas circuit interrupter including a pair of cooperablerelatively fixed nozzle-shaped contacts, a resilient rubber-like sleevecarrying one or more segmental movable bridging contacts for bridgingsaid pair of cooperable contacts in the closed circuit position,blast-valve means including a synchronous operator for effecting a blastof gas within said rubber-like sleeve only near a current zero on thedescending part of a fault-current wave, whereby said one or moresegmental contacts will draw arcs only near a current zero on thealternating current wave.

4. A circulatingsystem type of compressed-gas circuit interrupterincluding means defining a high-pressure storage tank, a relativelylow-pressure storage tank, a pair of cooperable relatively fixednozzle-shaped contacts, a resilient rubber-like sleeve carrying one ormore segmental movable bridging contacts for bridging said pair ofcooperable contacts in the closed circuit position, blast-valve meansincluding a synchronous operator for effecting a blast of gas withinsaid rubber-like sleeve only near a current Zero on the descending partof a fault-current wave, whereby said one or more segmental contactswill draw arcs only near a current zero on the alternating current wave.

5. The combination in a compressed-gas circuit interrupter of meansdefining a high-pressure chamber, means defining a low pressure chamber,conduit means including a double-damper synchronous valve and aninterrupting chamber interconnecting the two chambers, a synchronousoperator for actuating said valve on the descending portion of thecurrent wave, a pair of cooperable relatively fixed nozzle-shapedcontacts, a resilient rubber-like sleeve carrying one or more segmentalmovable bridging contacts for bridging said pair of cooperable contactsin the closed circuit position, whereby the arc will be drawn only neara current zero on the descending part of the fault current wave.

6. The compressed-gas circuit interrupter according to claim 5, whereinthe double-damper valve includes an open damper valve and a closeddamper valve.

7. A fluid-blast circuit interrupter including a nozzleshaped contacthaving radial slots thereon, insulating means disposed within saidslots, means including a cooperable contact for establishing an arcterminating on said nozzle-shaped contact, and means causing a radiallyinwardly directed fluid blast to blast through said nozzleshaped contactto effect extinction of said arc.

8. A fluid-blast circuit interrupter including a relatively stationarycontact structure comprising a spaced cooperable pair of nozzle-shapedcontacts having fluid-exhausting orifice openings therein, a surroundinginsulating flexible shell composed of an elastomeric material, one ormore bridging contact segments secured to and carried by the inner wallof said elastomeric shell, blast-valve means, means storing fluid underpressure, and opening of said blast-valve means releasing a blast ofhigh-pressure fluid interiorly within said shell to effect disengagementof said one or more bridging contact segments by outward bridgingdeformation of the shell.

9. The fluid-blast circuit interrupter according to claim 8, whereinmeans direct said fluid-blast radially inwardly between the spacedrelatively stationary nozzle-shaped contacts and axially outwardlythrough said exhausting orifices.

10. The fluid-blast circuit interrupter according to claim 8, whereinsaid blast-valve means includes a series control valve and a butterflyvalve actuated by a synchronous operator.

11. The fluid-blast circuit interrupter according to claim 8, whereinsaid blast-valve means includes a doubledamper valve, a synchronousoperator and a series control valve.

References Cited by the Examiner UNITED STATES PATENTS ROBERT K.SCHAEFER, Primary Examiner.

ROBERT S. MACON, Examiner.

1. THE COMBINATION IN A FLUID BLAST CIRCUIT INTERRUPTER OF A PAIR OFSPACED RELATIVELY FIXED NOZZLE-SHAPED CONTACTS, A PLURALITY OF MOVABLEBRIDGING SEGMENTAL CONTACTS FOR BRIDGING SAID PAIR OF SPACED RELATIVELYFIXED NOZZLE-SHAPED CONTACTS IN THE CLOSED CIRCUIT POSITION OF THEINTERRUPTER, EACH OF SAID SEGMENTAL BRIDGING CONTACTS HAVING A PISTONMEMBER SECURED THERETO, BLAST VALVE MEANS INCLUDING A SYNCHRONOUSOPERATOR FOR RELEASING A BLAST OF COMPRESSED FLUID INTO THE CIRCUITINTERRUPTER FOR ACTING UPON THE SEVERAL PISTON MEMBERS FOR EFFECTING ARCESTABLISHMENT, MEANS FOR DIRECTING THE FLUID BLAST RADIALLY INWARDLYTOWARD THE NOZZLE OPENINGS OF SAID PAIR OF RELATIVELY FIXED NOZZLESHAPEDCONTACTS, SAID SYNCHRONOUS OPERATOR BEING EFFECTIVE TO CAUSE BLAST VALVEOPENING ONLY NEAR A CURRENT ZERO ON THE DESCENDING PART OF THE CURRENTWAVE, AND A PAIR OF SPACED RELATIVELY FIXED ARCING ELECTRODES DISPOSEDALONG THE AXIS OF THE NOZZLE-SHAPED CONTACTS FOR POSITIONING THE ARCAXIALLY ALONG THE NOZZLE-SHAPED OPENINGS OF THE CONTACTS.